Fabrication of quantum dot/silica core–shell particles immobilizing Au nanoparticles and their dual imaging functions

• Published in: Applied nanoscience 2016-03, Vol.6 (3), p.301-307
• Main Authors: Kobayashi, Yoshio, Matsudo, Hiromu, Li, Ting-ting, Shibuya, Kyosuke, Kubota, Yohsuke, Oikawa, Takahiro, Nakagawa, Tomohiko, Gonda, Kohsuke
• Format: Article
• Language: English
• Subjects: Chemistry and Materials Science; Chest; Colloids; Core-shell particles; Gold; Materials Science; Mathematical models; Membrane Biology; Nanochemistry; Nanotechnology; Nanotechnology and Microengineering; Original Article; Quantum dots; Silicon dioxide; Walls
• ISSN: 2190-5509; 2190-5517
• DOI: 10.1007/s13204-015-0440-8

The present work proposes preparation methods for quantum dot/silica (QD/SiO 2 ) core–shell particles that immobilize Au nanoparticles (QD/SiO 2 /Au). A colloid solution of QD/SiO 2 core–shell particles with an average size of 47.0 ± 6.1 nm was prepared by a sol–gel reaction of tetraethyl orthosilicate in the presence of the QDs with an average size of 10.3 ± 2.1 nm. A colloid solution of Au nanoparticles with an average size of 17.9 ± 1.3 nm was prepared by reducing Au 3+ ions with sodium citrate in water at 80 °C. Introduction of amino groups to QD/SiO 2 particle surfaces was performed using (3-aminopropyl)-triethoxysilane (QD/SiO 2 -NH 2 ). The QD/SiO 2 /Au particles were fabricated by mixing the Au particle colloid solution and the QD/SiO 2 -NH 2 particle colloid solution. Values of radiant efficiency and computed tomography for the QD/SiO 2 /Au particle colloid solution were 2.23 × 10 7 (p/s/cm 2 /sr)/(μW/cm 2 ) at a QD concentration of 8 × 10 −7  M and 1180 ± 314 Hounsfield units and an Au concentration of 5.4 × 10 −2  M. The QD/SiO 2 /Au particle colloid solution was injected into a mouse chest wall. Fluorescence emitted from the colloid solution could be detected on the skin covering the chest wall. The colloid solution could also be X-ray-imaged in the chest wall. Consequently, the QD/SiO 2 /Au particle colloid solution was found to have dual functions, i.e., fluorescence emission and X-ray absorption in vivo, which makes the colloid solution suitable to function as a contrast agent for dual imaging processes.